Banking Web sites suffer from design flaws that undermine their security, exclusive of software vulnerabilities, according to a University of Michigan study to be released Friday.

Of 214 sites surveyed in 2006, more than 75 percent had at least one design flaw that could lead to a security problem, the university said. The flow and layout of the sites can make those sites riskier, and the problems can't be fixed with a patch unlike a software vulnerability.

A few of the study's findings were released on Tuesday by the university. The full findings will be presented at the Symposium on Usable Privacy and Security meeting Friday at Carnegie Mellon University in Pittsburgh.

The study was undertaken by Atul Prakash, a professor in the Department of Electrical Engineering and Computer Science, and two doctoral students, Laura Falk and Kevin Borders. Prakash began investigating after noticing problems with the Web site of his own bank, the university said.

Although the research was done in 2006, many of the problems still affect financial sites. One of the core troubles is an underutilization of SSL (Secure Sockets Layer) encryption technology on Web pages.

The study found that 47 percent of banks didn't use SSL on login pages, which could open the door for a hacker to reroute data to their own PC. Not using SSL also makes it easier for a man-in-the-middle attack, where the victim's data passes through an attacker's PC before it's routed to the bank's server.

Another pervasive problem affecting 55 percent of institutions is placing contact information and security advice on insecure pages. A hacker could conceivably break into the Web site and change the customer service phone number to direct banking customers to a fictitious call center. Again, SSL is the remedy.

The researchers found 30 percent of sites would redirect users to other Web sites, which can skew how a person is supposed to evaluate risk, the study said.

Since a bank site is trusted, the site it links to will likely not be considered a security risk even if it may be. Bank should put all their Web pages on the same server, but some have outsourced security features that are hosted on other domains.

Weak user IDs and passwords continue to be troublesome, with 28 percent of banks either lacking password guidelines or allowing weak ones. Institutions will also e-mail passwords or statements, which is also risky, the study said.